Sent an email, but will repeat it here to put it somewhere publicly.
eros is right now, out of action. It has been so since about electric - I've been helping them try and build up catkin - proof of concepting and prototyping through electric and fuerte so that cross-compiling is easier and eliminates all the hacks we were doing in eros.
Groovy's working now for us and that's the direction you should go in for cross-compiling. If you're not familiar with the catkin process I can help you there.
If you're just cross-compiling, that will work great. If you want to put an entire ros system on the core, you can probably pick up the recipes that I was using to cross-compile the dependencies. However, I'd actually recommend not putting the whole ros on an arm9 core. You don't have too many cycles there and you need every one you have for any robotics algorithm you're running. To get data back to a ros system in a compatible way, use rosserial with a serial link, or create your own custom protocol/bridge. Another alternative that I haven't tested yet but looks promising is https://github.com/openrobots-dev/uROSnode, which would let you run a lightweight c transport over the ethernet back to your main cpu. It's still early in development though.
Although I can't help you with your specific problem, I'd like to inform you about the embedded SIG (Special Interest Group). eROS is a special case, but for other embedded issues, you might find help there.
Thanks for your help :)
You are welcome. Another small comment from myself: If your questions has been answered, e.g. by Daniel's answer below, please mark your question as answered. Thank you!